1. Field of the Invention
This invention relates to a process for producing nitrite cured ham and bacon which is not susceptible to contamination from Clostridium botulinum, and which will not produce carcinogenic products upon cooking.
2. Discussion of the Prior Art
Normally a nitrite salt is added to ham and bacon at a ratio of 120-156 ppm as NaNO.sub.2, together with sodium chloride, for the purposes of (1) inhibiting growth of bacteria which cause food poisoning, particularly Clostridium botulinum, (2) stabilizing the color of meat, (3) imparting a favorable flavor to cured meat, and (4) retarding the spoilage of meat.
The usual means for adding the nitrite salt to the meat include, for example, sprinkling a powdery curing agent on the meat as it is, or injecting a pickle solution into the meat, or dipping the meat in the pickle solution.
Of the above activities of nitrite, the most important from the standpoint of food sanitation is the antibotulinal activity. If the nitrite is reduced or not used, the growth of Clostridium botulinum cannot be inhibited, and the deadly poison produced thereby will cause extremely dangerous food poisoning.
With the view to preventing reducing danger, the addition of a nitrite by 120-156 ppm as NaNO.sub.2 as aforesaid is practiced in the United States, and this addition level is deemed to be absolutely necessary for achieving the intended purpose.
The use of nitrite represented by NaNO.sub.2, however, has been found to give rise to the following problems. To wit, (1) formation of nitrosamines in the meat by the reaction of secondary amines or amino acids with nitrite is observed. Particularly in bacon the reaction of L-proline, an amino acid, with nitrite under the cooking heat produces N-nitrosopyrrolidine (NPYR). These nitrosamines are invariably strong carcinogens for animals. (2) Nitrite itself has been recently reported to be carcinogenic by Newbern et al. of MIT, and it is suspected that similar research results may be reported in the future. (3) Nitrite is extremely reactive. For example, its reaction with compounds containing double bonds, or its amino acid-decomposing reaction, or its reaction with hydroxyl group-containing compounds have been confirmed. The majority of the products of its reactions with such various organic compounds are mutagens.
Based on the foregoing facts, there is a possibility that people who eat nitrite-added ham and bacon may have a higher risk of cancer.
It is a vital necessity, therefore, to reduce the amount of nitrite radicals (NO.sub.2.sup.-) added for making safe meat products, such as ham and bacon, to start with.
The reduction in the amount of NaNO.sub.2, however, makes it impossible to inhibit the growth of Clostridium botulinum as aforesaid, inviting a serious food sanitation problem.
Furthermore, addition of erythorbic acid and the salts thereof, ascorbic acid and the salts thereof, their higher fatty acid esters and their higher acetals, as well as tocopherols, to the meat has been attempted for the purpose of preventing the formation of nitrosamines.
Consequently, it became apparent that some other means had to be employed for reducing NaNO.sub.2, inhibiting the formation of nitrosamines such as NPYR, and still inhibiting the growth of Clostridium botulinum. For example, utilization of sorbic acid or its salts as the preservative may be considered.
The reduction in NaNO.sub.2 also impairs the stability of meat color. Hence it becomes necessary to add an enediol type reducing agent such as sodium erythorbate, in addition to the nitrosamine formation-inhibiting agents as aforesaid.
In the past it was attempted, therefore, to mix NaNO.sub.2, sodium erythorbate (NaEry) and potassium sorbate (SoK) into a pickle solution concurrently, and inject the solution into a meat lump for making meat products, e.g., bacon.
When such a method is employed, however, the high reactivity of NaNO.sub.2 with the various componds as aforesaid presents a very serious problem. For example, the reaction of NaNO.sub.2 with sorbic acid has been confirmed by studies reported in the following publications.
Chemistry and Biology 17 361 (1978) PA1 Arg. Biol. Chem., 39 1335 (1975) PA1 Rev. Polarogr. 34 45 (1978) PA1 Tetrahedron 34 505 (1978) PA1 IARC Sci. Pub. No. 12 Screening Tests in Chemical Carcinogenesis 105-115 PA1 Mut. Res. 30 417 (1975) PA1 Mut. Res. 53 206 (1978) PA1 (1) effective inhibition of formation of nitrosamines in general, as well as NPYR, PA1 (2) reduction of nitrite radicals remaining in the meat, PA1 (3) powerful antibotulinal activity with the reduced nitrite radicals, and PA1 (4) stabilization of favorable meat color. PA1 (1) separate addition to the meat of (A) an additive composition including amino acid-type condiments, sorbic acid and the salts thereof or C.sub.8 -C.sub.12 glycerol fatty acid esters which show antibacterial activities, erythorbic acid and the salts thereof, ascorbic acid and the salts thereof, and their higher fatty acid esters, their higher acetals or tocopherols and (B) a NaNO.sub.2 -containing additive, PA1 (2) when an organic acid or acids and/or acidic inorganic salt or salts are added to the above (A) additives, separate addition to the meat of such (A) additives and (B) a NaNO.sub.2 -containing curing agent, in order to increase the effect of the above-named preservative as well as to avoid their reactions with NaNO.sub.2.
Furthermore, the formation of an ether-extractable, recassay positive substance by a reaction between NaNO.sub.2 and sodium erythorbate at such high concentrations as used in the conventional pickle solutions has been recognized. Also when certain amino acids are reacted in the presence of NaNO.sub.2 at a high concentration, they are completely decomposed. Hence, addition of mixed amino acids as condiments to the pickle solution must be avoided.
A reaction between NaNO.sub.2 with tyrosine was reported in J. Food Sci., 41, 585 (1976), and that with tryptophane to form nitrosotriptophane was reported in Can. J. Biochem., 50, 1282 (1972).